1. Field of the Invention
The present invention relates to an arrangement for securing a handle or an operation handle to a drive shaft in an automotive seat, as with a handle for operating such device as a lumbar support device or a seat position adjustment device.
2. Description of Prior Art
Reference is made to FIGS. 1, 2, 3A and 3B which show a conventional handle securing arrangement for use with a lumbar support device (not shown).
Referring to FIGS. 2, 3A and 3B, reference numeral (1) denotes an operation handle for controlling motions of the lumbar support device. The operation handle (1) has a hub (1a) for spline connection with a drive shaft (2). In this type of handle securing arrangement, the hub (1a) is formed, at each of its lateral sides, with a slit (1b) opened generally along the semi-circular cross section of the hub (1a), forming thus a pair of spaced-apart slits (1b)(1b) circumferentially of the hub (1a), at the right and left sides symmetrically relative to the central axis of the hub (1a), with the formation of the drive shaft (2) being that its forward end is machined in a male threaded way, forming a male threaded spline portion (2b) to be spline connected into a female threaded portion formed in the hub (1a), and that a circular recessed groove (2a) is formed such as to be disposed generally in alingment with the two slits (1b) of the hub (1a). As shown in FIG. 3A, when spline connecting the hub (1a) to the drive shaft (2), a snap ring (3) is attached into the juxtaposed slits (1b) and groove (2a) from both sides of the hub (1), thereby resiliently retaining the operation handle (1) against removal or falling-off out of the shaft (2).
However, as seen from FIG. 3B, the fact that both slits (1b) and groove (2a) are greater in in dimensions than the cross-sectional outer diameter of the snap ring (3), in particular, as indicated by the designation (L1), conventionally, the groove (2a) of the shaft (2) is of a great width relative to that of the slits (1b), results in creating a play for the snap spring (3) and thus causing an unstable sliding movement or wobbling of the handle (1) upon the shaft (2) in the axial direction, as understandable by the arrow in FIG. 3A. Consequently, such wobbling of the handle (1) emits an unpleasant noise to pose a disadvantageous problem in controlling the lumbar support device.